The present invention relates to a method for producing a mineral enriched protein composition which is used in the production of foodstuffs, particularly liquid foodstuffs such as dietary and nutritional beverages.
Protein isolates that are derived from vegetable protein sources, such as soybeans have contributed substantially to the economic importance of these materials as a crop. Soy protein isolates in particular have proven to be a useful nutritional supplement in a variety of foods and beverages. A protein isolate can be generally characterized as a product resulting from the extraction, subsequent concentration, and purification of proteinaceous material from a proteinaceous source such as a vegetable protein material. Typically, the protein isolate on a moisture free basis will have a protein content which will range between about 90% and 98% by weight.
The usefulness of soy protein isolates in the formation of foodstuffs such as beverages has for the most part been accomplished by the production of modified or enzymatically hydrolyzed isolates or the addition of materials such as surfactants to promote the dispersibility or suspendibility of the isolate in the particular type of aqueous medium that is used in preparation of the beverage.
An example of this type of protein product, is described in U.S. Pat. No. 4,378,378 in which a simulated milk product of improved suspension characteristics is produced wherein a slurry of a vegetable protein material and dairy whey is formed, followed by the reaction of the slurry with a proteolytic enzyme. While protein isolates are generally dispersible in aqueous mediums, nevertheless it has been more difficult to employ these isolates in conjunction with certain vitamins and minerals that may be required, if a nutritionally complete beverage or drink, such as an infant formula is produced. For example, fortification of a liquid product with calcium represents a particular problem, since most forms of calcium that are employed for calcium supplementation in nutritional beverages are relatively insoluble in aqueous mediums. These materials readily precipitate or settle from aqueous suspension, thereby providing the user with a drink that must be shaken relatively often to ensure adequate consumption of the minerals in the diet.
Dispersibility of a mineral enriched protein composition has been described in U.S. Pat. No. 4,214,996, in which the mineral is chelated with an organic acid and a sugar for purposes of improving the dispersibility of the minerals in an aqueous medium such as a beverage. It is indicated that the product can be dried and reconstituted with good results.
An alternative approach to the dispersibility of specific mineral fortifying substances, such as calcium phosphate, is set forth in U.S. Pat. No. 2,605,229. This describes the production of a calcium phosphate gel which will remain dispersed in water when mixed therewith to yield a milky suspension simulating the dispersion of calcium phosphate in milk.
It would be desirable if a minerally enriched protein composition could be developed of improved suspension characteristics in which no significant precipitation of the minerals or protein medium would occur particularly upon prolonged storage of the beverage or liquid foodstuff to which the composition is added.
It is therefore an object of the present invention to develop a method for the production of a mineral enriched protein composition that can be used in the production of liquid foodstuffs in which the mineral enriching components contained in the protein material substantially remains in suspension even during periods of prolonged storage.
It is a further object of the present invention to produce a mineral enriched or calcium fortified protein composition having improved suspension characteristics in liquid foodstuffs.